Adding a little push-up to a basic runner's lunge deepens the stretch for your hip flexors, the muscles on the front of the hip joint, while moving in and out of a plank warms up your core.
- Start in plank position, and bring your right foot to the outside of your right hand. Bend your elbows slowly to deepen the stretch.
- Return your right leg back to plank position, and repeat on the other side. This completes one rep.